Support Bot as an actor

[khoinguyen]

trafficstars

In my use case, I make several commands as building blocks, then I have a cron workflow to trigger the commands in some sequences. In that case, I want to have the comment as a bot to differentiate between comments from contributors and scheduled actions. The bot token is perfect in this case, IMO.

This PR tested in my case. Just add allow-bots input to, of course, allow to dispatch the commands.

As a preventive, the bot name must be ends with [bot] as per GitHub action convention

with:
  allow-bots: hello[bot]